System and method for detecting a condition indicative of plugging of a discharge path of an agricultural combine

ABSTRACT

A system and method for detecting a condition indicative of onset of plugging or actual plugging of a discharge of an agricultural combine, utilizing a pressure sensor disposed at a location within the combine spaced from the discharge and operable for sensing an air pressure condition relating to a flow indicative of a reduced crop residue flow condition toward or in the discharge.

TECHNICAL FIELD

The present invention relates generally to a system and method fordetecting a condition indicative of plugging of a path for dischargingcrop residue from an agricultural combine, and more particularly, fordetecting a condition indicative of the onset of plugging, to allowavoiding occurrence of actual plugging and the requirement of removingthe plug.

BACKGROUND ART

Agricultural combines are well known in the art for harvesting andthreshing various agricultural crops, including for example, wheat,soybeans, corn, etc. Usually, agricultural combines include a harvestingapparatus, an infeed mechanism, a separating apparatus and a cleaningapparatus. In operation, the harvesting apparatus reaps the crop, whichis planted in the ground. After reaping, the infeed mechanism feeds thecrop to the separating apparatus.

Typically, the separating apparatus in a rotary combine includes atleast one rotor, which can extend axially (front to rear) ortransversely within the body of the combine, and which is surrounded atleast in part by a perforated concave having a plurality of apertures.The grain is threshed and separated by the separating apparatus, and theseparated grain, together with some impurities, such as chaff, dust, andcrop residue particles, are fed to a cleaning system to clean theimpurities from the grain. Clean grain is collected below the cleaningsystem and fed to a grain tank for temporary storage. The clean grain,impurities and smaller elements and particles of the crop residue areseparated form the bulk of the crop residue by the separating apparatusand the resulting residue is delivered for processing by a dischargedelivery system.

While the terms “grain” and “crop residue” are used principallythroughout this specification for convenience, it should be understoodthat these terms are not intended to be limiting. Thus “grain” refers tothat part of the crop which is threshed and separated from thediscardable part of the crop material (e.g. straw), which is referred toas “crop residue”.

Traditional discharge delivery systems rely on a device often referredto as a “straw walker” or another device known as a “discharge beater”,to transport or convey the separated crop residue rearwardly within abody of the combine to a residue handling system. Generally, strawwalkers, which involve crank mechanisms for conveying the crop residue 2b rearwardly through a combine, are relatively slow in operation andthus have a limited material handling capability or rate. The crankmechanisms add complexity and vibration. Discharge beaters “throw” orpropel the crop residue away from the separator and toward the rear ofthe combine. In both instances, the crop residue can be dischargeddirectly in its raw form through a rear opening of the combine onto theharvested field; it can be directed into a chopper mechanism inconnection with the rear of the combine which chops the crop residue andthen discharges it onto the harvested field; or the chopper can functionjust as a spreader for spreading the unchopped crop residue onto thefield.

Today's new, improved combines have greater harvesting and threshingcapacities. Although discharge systems such as briefly discussed abovehave also improved, the harvesting and threshing systems of moderncombines can at times produce volumes of crop residue material that canexceed the capacity of the discharge systems, leading to pluggingthereof and packing of crop residue thereagainst and over the cleaningsystem, which can require substantial down time and effort to remove. Insome instances, the only warning of plugging is when an operator noticesthat crop residue is no longer being discharged or is being dischargedat a rate which appears to be too low or the pattern of discharge isincorrect. Therefore, it would be advantageous if accurate early warningor information indicative of a plugging condition, or onset of aplugging condition, were provided, to allow an operator or automaticcontrol to take steps to avoid plugging, or shut down the machine forremoving the plug and/or cleaning, before significant down time andeffort is required to do so.

As an additional problem, if crop residue falls short of the rear of thecombine, blockages and interference with and reduction in theeffectiveness in the operation of the chaff handling system of thecombine can occur, thereby also resulting in combine down time,decreases in harvesting productivity, and increases in operator andowner dissatisfaction and component failure. Therefore, it would beadvantageous to avoid this problem also.

Accordingly, what is sought is a system or method for detecting aplugging of a crop residue discharge of a combine which provides one ormore advantages, and overcomes one or more problems, set forth above.

SUMMARY OF THE INVENTION

With this invention, a system and method for detecting a conditionindicative of onset of plugging or actual plugging of a discharge of anagricultural combine, which provides one or more of the advantages, andovercomes one or more problems, set forth above, is disclosed.

According to a preferred aspect of the invention the combine includes abody defining a space containing a separating apparatus or system, and arear opening spaced rearwardly of the separating system. A rotary beateror other propeller device is disposed in the space between theseparating system and the rear opening and operable for propelling aflow of crop residue rearwardly along a crop flow path from theseparating system toward a rear end of the space. The combine includes acleaning system disposed in the space below the rotary beater andincluding a fan disposed for directing a flow of air rearwardly throughan air flow channel through the space between the cleaning system andthe beater, and an air pressure sensor is disposed in the space so as tobe operable for sensing an air pressure condition therein indicative ofa reduced crop residue flow condition toward the rear end of the space.

This location is advantageous, as it locates the air pressure sensor outof the actual crop residue flow, and away from an actual pluggingcondition. Instead, the invention utilizes detected changes orvariations in air pressure conditions at the location remote from theactual plugging condition, to enable determining the presence ofconditions indicative of the onset of plugging and/or actual plugging,such that the detector, here, an air pressure sensor, is not subjectedto adverse conditions of plugging, such as, but not limited to, beingclogged or plugged with crop material, dust, or the like. Here, itshould be recognized and understood also that pressure conditions at thelocation of the sensor can be affected by changing parameters, which caninclude ambient air conditions and moisture content and consistency ofthe crop residue, as well as different discharge apparatus set ups, forinstance, a set up for directing crop residue into a chopper forchopping thereby; a set up for just spreading the crop residue; a set upfor windrowing; and/or a set up for mixing chaff with the crop residue,and aspects of the system of the invention can be adapted for factoringsuch variables when determining the existence or non-existence of aplugging condition. Additionally, the criticality of plugging under aparticular discharge set up can be a factor. For instance, ifwindrowing, the clearing of a plug may not be as difficult and/or timeconsuming, compared to if the inlet of a chopper is plugged, and thesystem can be adjusted or calibrated to output a warning or makeadjustments accordingly. For instance, when windrowing, a warning of aplugging condition may be outputted at a later time compared to ifchopping crop residue. According to another preferred aspect of theinvention, the combine includes a pan or concave disposed in the spacebeneath the beater and above the air flow channel, for guiding the cropresidue flow propelled by the beater, and the air pressure sensor ispreferably disposed below the concave. The cleaning system can furtherinclude a generally flat, horizontal sieve disposed below the air flowchannel, and the air pressure sensor is preferably disposed above thesieve. This location, below the concave and above the cleaning systemsieve, places the sensor in a flow channel for air from a fan of thecleaning system, and it has been found that air pressure conditions atthis location are good indicators of the onset and existence of pluggingconditions more rearwardly in the discharge area of the combine.

According to still another preferred aspect of the invention, a cropresidue chopper is disposed in connection with the rear opening, and aconveyor mechanism is disposed in a rear region of the space in aposition for receiving at least a portion of the flow of the cropresidue from the beater and conveying the received flow into thechopper, the air pressure sensor being operable for sensing an airpressure condition indicative of plugging involving the conveyormechanism.

According to still another preferred aspect of the invention, thecombine includes a control in connection with the air pressure sensor,and a device for determining a speed of the conveyor mechanism, and thecontrol is operable for determining existence of onset of or an actualplugging condition involving the conveyor as a function of conveyorspeed. The control can also be operable for determining a new speed forthe conveyor mechanism as a function at least in part of a sensed airpressure and determined speed of the conveyor. In another preferredaspect, the combine includes a device for determining a speed ofrotation of the beater, and a device for determining a speed of the fan,and the control is operable for existence of onset of or an actualplugging condition as a function at least in part of a sensed airpressure and a determined speed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the present invention are best understoodwith reference to the drawings, in which:

FIG. 1 is a side view of an agricultural combine including a systemaccording to the invention for detecting plugging of a discharge of thecombine;

FIG. 2 is a simplified schematic representation of a separating systemand a cleaning system of the combine in association with the system ofthe invention, showing flows in relation thereto;

FIG. 3 is simplified schematic representation of aspects of a system ofthe invention;

FIG. 4 is a fragmentary sectional view of a side sheet of the combineand an air pressure sensor of the invention mounted therethrough;

FIG. 5 is another simplified schematic representation of the separatingsystem and the cleaning system of the combine in association with thesystem of the invention, showing plugging in a discharge region andresultant changes in flows through the combine;

FIG. 6 is a simplified schematic illustration of open flow through thecombine; and

FIG. 7 is another simplified schematic illustration of plugged flowthrough the combine.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, FIGS. 1 and 2 show a self-propelled rotarycombine 20 that includes a housing or body 22 defining an internal openarea or space 24. While a conventional rotary combine is shown, it isanticipated that the present invention could be used with any type ofcombine, such as a conventional combine having a threshing cylinder andseparation beaters (not shown) or a hybrid combine having a threshingcylinder and rotors (not shown). However, for ease of explanation, thepresent invention will be discussed hereinafter in conjunction with aself-propelled rotary combine 20 as illustrated by FIGS. 1 and 2.

The body 22 of the combine 20, which can include a supporting frame 26,is supported on front drive wheels 28 and steerable rear wheels 30. Thecombine 20 is powered by an engine (not shown) and controlled from anoperator's station 32.

A crop harvesting apparatus, otherwise referred to as a header 34, andan infeed mechanism 36 are attached at a forward end of the combine 20.The infeed mechanism 36 feeds crop materials to a separating system 38enclosed within the body. One example of a rotary combine configuredwith a rotary assembly is disclosed in U.S. Pat. No. 5,489,239, titled“Rotary Combine” and which issued Feb. 6, 1996 to Case Corporation, andwhich is hereby incorporated herein by reference.

As best shown in FIG. 2, the separating system 38 is preferablyconfigured as a single axial unit that threshes and separates cropmaterials presented thereto into grain and other materials. However, itshould be appreciated that the rotary combine 20 could be configuredwith more than one separating system 38, for example, with two unitsarranged in a parallel configuration. The separating system 38 ismounted in the internal space 24 defined by body 22.

The separating system 38 includes a rotor 40 with a longitudinal extentrotatably mounted to the body 22 about a longitudinal axis of rotation42. It should be understood that the term “longitudinal” means of orrelating to length or the lengthwise dimension. It should also beunderstood that the rotor 40, with its longitudinal extent, could bemounted within the body 22 so as to extend laterally from side-to-sidewithin the combine 20.

It should be understood that the terms “left side,” “right side,”“left,” “right,” “front,” “rear,” “upper,” “lower,” “top,” and “bottom,”and their derivatives, as used herein, are intended to indicatedirections relative to the views presented in the FIGS., and inparticular, when viewing the rotary combine 22 of FIG. 1, and theinternal components thereof.

Between the upstream, or front end 44, and the downstream, or rear end46, of separating system 38, the crop material is threshed as it spiralsaround rotor 40 against a concave 48 disposed at least partially,circumferentially around rotor 40. The rotor 40 can be dimensioned witha broad range of diameters, depending on the desired size andperformance characteristics of the combine 20.

Concave 48 has a plurality of apertures that allow the grain to beseparated from the other crop material as the grain passes through theapertures. Most of the grain drops onto a grain pan 50. The grain isthereafter conveyed rearward from the grain pan by an auger or othersuitable mechanism (not shown) for subsequent cleaning and collection bya cleaning system 52.

The cleaning system 52 cleans chaff, crop residue, tailings and otherforeign material from the grain. Cleaning system 52 includes a cleaningfan 54, a chaffer sieve 56, a grain sieve 58, and a clean graincollector therebelow (not shown). A suitable auger mechanism (also notshown) can direct clean grain from the clean grain collector into ahopper or grain bin 60. The cleaning fan 54 directs a flow of air,denoted by large arrow A, upward and rearwardly through sieves 56 and58, and rearwardly, for blowing the chaff and other particles from thegrain.

Crop residue and other waste crop material are impelled rearwardly outof rear end 46 of separating system 38 by a rotary beater 62 whichrotates, as denoted by arrow B to “throw” or propel, as denoted byarrows B1 and B2, an airborne flow of crop residue and other wastematerial, particularly straw, through the space 24 rearwardly toward therear end of the space 24 and the combine 20. The beater 62 is preferablypositioned above a beater pan 64 to facilitate this function. Suchairborne flow of the crop residue will typically comprise elements ofvarying size, mass and other characteristics that will influence thedistance that the elements of the crop residue will be thrown orpropelled through the space 24, and also the propensity for plugging Forinstance, it can be expected that a wad or wads of weeds vines or toughor green crop residue propelled rearwardly by beater 62 will not travelas far through space 24 compared to lighter individual elements of thecrop residue such as individual straws and the like. This can be due tothe larger size of the wad, and also greater weight compared to thelighter elements. As a result, it has been found that such wads andlarger and/or heavier elements of the crop residue can have a tendencyto fall down at more forward locations within the space 24. Moistureconditions such as humidity and moisture content of the crop residue canalso be a factor in propensity toward plugging.

To overcome the problem of short falling crop residue, and alsoplugging, combine 20 further preferably includes an optional conveyingmechanism 66. Conveying mechanism 66 is preferably mounted to the bodyof the combine 20 in a position such as that shown, in spanning relationto a portion of space 24 just below, or in a lower region of, a path ofthe rearward flow generated by beater 62, denoted by the arrows B1 andB2. Advantageously, conveying mechanism 66 will be positioned in thepath of elements of the crop residue flow B, B1 and B2 that would fallshort of a desired destination therefor, such as a rearwardly locatedchopper 68 or an outlet opening, and so as to prevent or limitoccurrences of problems including blocking and interfering with theoperation of other systems. At the position shown, the front end of theconveying mechanism 66 is located above at least a rear end of a lowerrear opening 70, which coincides with a location of most anticipatedshort falls of crop residue flow B, B1 and B2.

The conveying mechanism 66 can be optionally mounted for pivotalmovement in an upward and downward direction, for operation in analternative position, desired or required for a particular application.

The conveying mechanism 66 includes a conveyor drive 72, which can be,for instance, a well known, commercially available hydraulic motor, anelectric motor, etc., drivingly rotatable for continuously moving anupwardly facing conveyor surface 74 of conveying mechanism 66 in therearward direction, as denoted by arrow C. Conveyor surface 74 ispreferably a surface of an endless belt, chain or the like whichencircles rollers at the opposite ends of conveying mechanism 66, andcan have a generally smooth surface, or a textured surface, or includeraised elements thereon, as desired or required for a particularapplication. The conveyor drive 72 is shown connected in drivingrelation to one of the rollers for moving conveyor surface 74 in thewell known manner.

The conveying mechanism 66 can additionally be optionally rotatable bydrive 72 at variable speeds, either under manual control, orautomatically responsive to and in adjustment for differentcharacteristics of the crop residue being received and/or otherconditions, as represented by one or more predetermined parameters. Thiscan include an indication of an onset of a plugging condition involvingmechanism 66. Generally, the conveying mechanism 66 is bounded on itsupper side by a crop residue hood ceiling 76, which prevents cropresidue from escaping upward. The conveying mechanism 66 cooperates withcrop residue hood ceiling 76 for merging portions of, shaping, andregulating crop residue flow B, B1 and B2, as will also be explained.Hood ceiling 76 can also be opened, for configuring to allow outflow ofcrop residue for windrowing.

Located generally below the conveying mechanism 66 can be other optionalcrop residue processing mechanisms. For example, crop residue chopper68. It is contemplated that the chopper 68 can be any conventionalchopper currently known in the art or any improved version thereof, forchopping and/or spreading crop residue. Regardless, it is preferred thatthe chopper 68 include a chopper housing 78 having an inlet opening 80for receipt of crop residue, such as straw. Located rearward of thechopper 68 is preferably a chopper spreader band or guide 82, fordirecting the crop residue discharged from chopper 68 in a desiredmanner over a field, and when windrowing, for guiding crop residueejected from open hood ceiling onto a field therebelow.

FIG. 2 shows the conveying mechanism 66 mounted adjacent to and inspaced relation below, the crop residue hood ceiling 76 of the combine.As illustrated, it is contemplated that the discharge beater 62 willthrow or propel a flow of crop residue rearwardly, denoted by arrows B1and B2, such that some or all of the crop residue, particularly largerelements and wads thereof, represented by arrow B1, will fall or landupon the conveying mechanism 66, and more particularly, on conveyorsurface 74, which is moving rearwardly as denoted by arrow C. The movingsurface 74 will carry the crop residue deposited thereon rearwardly soas to effectively be merged or mixed with the still airborne cropresidue flow B2, which is at the same time being guided downwardly bythe hood ceiling 76, so as to reduce the overall vertical extent of thecrop residue flows B1 and B2, so as to be more uniform and consistent.The rearward powered movement of surface 74 of conveying mechanism 66thus facilitates the collection and consolidation or funneling of thecrop residue discharge, and positively delivers it, to the chopper 68,as denoted by arrow E. In this regard, it should be appreciated thatelements of the crop residue flow B1 that fall onto conveyor surface 74will often have little or no useful remaining rearward velocity ormomentum, and thus will be accelerated and positively propelledrearwardly to the rear end of the conveyor surface 74 and be combinedwith flow B2. The rearward movement of and energy imparted to the thusconveyed crop residue of flow B1 will facilitate the merging and mixingthereof with the still airborne portions of the crop residue flow B2,and also the smooth feeding of the combined and merged crop residue flowE into the chopper 68. In this latter regard, the reduced or controlledvertical extent of the combined crop flows B1 and B2 facilitate moreuniform, controlled and concentrated entry and feeding of the crop flowE at a desired angle and location into inlet opening 80 of the chopper68. And, in the event of receipt of a particularly large volume or wadof crop material, the combination of the powered conveying mechanism 66positively driving the crop material rearwardly and the reducing of thevertical extent thereof will have the effect of throttling and funnelingthe crop material into the chopper 68 so as to regulate the flow of thecrop material inducted therein and reduce the occurrence of induction ofwads and large volumes that can overload the chopper and cause problemssuch as excessive drive belt slippage and resultant wear.

Here, it should be noted that the conveyor surface 74 of the conveyingmechanism 66 can additionally be optionally automatically moved in adifferent opposite direction D by drive 72, and at variable speeds,either under manual control using a suitable input device in operator'sstation 32 or elsewhere, or automatically, responsive to and inadjustment for different characteristics of the crop residue beingreceived and/or other conditions, as represented by one or morepredetermined parameters. Such parameters can include, for instance, butare not limited to, parameters sensed or determined by an element orelements of the header 34, the infeed mechanism 36, the separatingsystem 38, and/or the cleaning system 52, and/or sensors associated withthe conveying mechanism 66, such as a load sensor (not shown) associatedwith surface 74 for sensing a load thereon, or a contact switch (notshown) disposed above the surface 74 which will make or break anelectrical circuit responsive to contact with a mass of crop residue orstraw being conveyed by the surface 74 or being fed into one of theprocessing devices such as the chopper 68, or rearwardly from thecombine. The speed can be controlled by a processor based control, suchas a control 84 (FIG. 3), which can be connected to the drive 72 by asuitable conductive path, such as wire 86 shown. By such control theconveyor surface 74 can be sped up or slowed down, as required ordesired to regulate crop residue flow into the chopper 68 for optimizingoutput therefrom and for regulating the characteristics, such asconsistency, cohesiveness and the like, of a windrow (not shown).

Referring also to FIG. 3, a schematic representation of a preferredprocessor based control 84 for combine 20, is shown. More particularly,control 84 is connected by a connective path 86 to a cleaning fan drive88 controllably operable for rotating cleaning fan 54 at a desired orrequired speed determinable by drive 88. Control 84 is also connected toa rotor drive 90 by a conductive path 86, drive 90 being controllablyoperable for drivingly rotating rotor 40 of separating system 38 anddetermining a speed thereof. Control 84 is connected by a conductivepath 86 to a beater drive 92 controllably operable for rotating beater62 and determining a rotational speed thereof. Similarly, control 84 isconnected by a conductive path 86 to a feeder drive 94 of infeedmechanism 36 for controlling and determining an operating speed thereof.An output device 96 is connected by conductive path 86 to control 84,and is operable for displaying and/or signaling conditions as determinedby control 84.

Control 84, and the various aspects thereof, just discussed, importantlycomprise elements of a system 98 for detecting a condition indicative ofonset of or actual plugging of a discharge path for crop residue fromcombine 20, constructed and operable according to the teachings of thepresent invention. System 98, importantly, includes a sensor 100disposed in space 24 so as to be operable for sensing a conditiontherein which is indicative of a reduced crop residue flow conditiontoward the rear end of space 24, which reduced crop residue flowcondition can include, but is not limited to, a partial or completeplugging or blocking of the rear region of space 24 between conveyingmechanism 66 and hood ceiling 76, as illustrated by crop residue plug102 between conveying mechanism 66 and hood ceiling 76 in FIG. 5.

Referring also to FIGS. 4 and 5, sensor 100 is preferably an airpressure sensor which can be, for instance, a commercially availabledifferential pressure transducer available from Kavlico, of Moorpark,Calif. USA, operable for sensing and detecting changes and variances inair pressure. Sensor 100 is preferably a model threadedly mountable in ahole 104 in a side wall or sheet 106 of body 22 of combine 20. Sensor100 is preferably of at least generally well known constructionincluding a port 108 in connection with space 24, and another port 110in connection with another location, such as ambient conditions on theexterior of combine 20, and is operable for sensing and detectingdifferences in pressure in respective ports 108 and 110, and outputtinga signal representative thereof over a suitable conductive path, such asa wire 86 in connection with control 84, as illustrated in FIG. 3. It isdesirable for sensor 100 to be operable for detecting conditions,particularly air pressure conditions, and more particularly, static airpressure conditions, in a region of space 24 of combine 20 which will beindicative of the onset of, or actual, plugging of all, or a portion of,a discharge of combine 20, generally denoted by region 112 in FIGS. 2and 5. More particularly, discharge 112 can include, the region betweenconveying mechanism 66 and hood ceiling 76, the inlet opening 80 ofchopper 68, and/or lower rear opening 70, as well as any other aspect ofcombine 20 involving discharge of crop residue therefrom involvingoutflows of crop material from separating system 38 and/or cleaningsystem 52.

As a preferred location for sensor 100, it has been found that pressureconditions of air flow A generated by cleaning fan 54 and directedthrough and over chaffer sieve 56 toward the rear end of space 24 willbe increased by the onset of, and actual, plugging of one or moreregions of discharge 12, such as, but not limited to, the region betweenconveying mechanism 66 and hood 76, as illustrated by plug 102 in FIG.5, even though such plug 102 is located virtually at the opposite end ofspace 24 within the combine. It has been further found that in theregion of space 24 between chaffer sieve 56 and beater pan 64, staticair pressure conditions can be sensed which will be indicative ofconditions elsewhere in space 24, particularly in discharge 112, and ithas been concluded that sensing of such air flow conditions at suchlocation, as illustrated by the location of sensor 100 in FIGS. 2 and 5,is highly advantageous for monitoring operating conditions in discharge112. As another advantage, the region of space 24 between beater oen 64and chaffer sieve 56 is much less subject to blockage or plugging, suchthat reliability of operation is enhanced. As an example, referring moreparticularly to FIG. 5, a plug 102 can virtually fill the space betweenconveying mechanism 66 and hood ceiling 76, without resulting in anyplugging or significant buildup of crop material in the vicinity ofsensor 100 when located as shown. However, it has been found that theexistence of a plug such as plug 102 which partially or completelyblocks the pathways for discharge of air from space 24, will result inan increase in static air pressure in the vicinity of sensor 100, asillustrated by large arrow A1. This increase in pressure will bedetected by sensor 100 and information relating thereto outputted bysensor 100 to control 84 of system 98 (FIG. 3). Control 84, in turn, isoperable, for instance, to compare the information to stored valuescorresponding to other parameters, such as a speed of cleaning fan 54,to determine the existence of a plug, such as plug 102, or the onset ofthe formation thereof. An advantage of utilizing sensed air pressure inthe above-described manner, is that the pressure can be incrementallydetermined, and, for instance, an upward trend detected, which may bedetermined to be indicative of the onset of a plugging condition. Otherparameters or conditions can also be factored, including, but notlimited to, load on and/or speed of conveying mechanism 66; speed ofbeater 62; speed of rotor 40; and/or speed of infeed mechanism 36. Oncethe existence of the onset of, or an actual plugging condition, isdetermined, control 84 can be programmed to output a signalrepresentative thereof, for instance, to output device 96, and/orcontrol 84 can automatically adjust one or more operating parameters,such as, but not limited to, any or all of the speeds of infeedmechanism 36, separating system 38, beater 62, conveying mechanism 66,and/or chopper 68, for mitigating or clearing the condition, or allowingits removal. Comparing air flow patterns (large white arrows) indischarge 112 of combine 20 in FIGS. 2 and 5, representative of a clearcondition, and a plugged condition, respectively, it can be seen that aplug such as plug 102 in FIG. 5 will cause a diversion of normal airflow patterns, as well as at least some crop residue flow from flows B1and 2, downwardly toward and through lower rear opening 70, therebycreating an increased pressure condition A1 in the region of sensor 100.Essentially, this can be summarized as a back pressure condition createdas a result of limiting out flow paths for air through discharge 112.Control 84 can be programmed to differentiate between ranges ofpressures sensed under conditions represented by FIGS. 2 and 5,respectively, for determining existence of a plugging condition (FIG.5), and also the onset of such a condition. Responsively, control 84 canoutput an appropriate signal to output device 96 to alert an operatorwho, in turn, can responsively take an appropriate action, such as, butnot limited to, halting operation of combine 20 and manually clearingthe plug, altering an operating condition of conveying mechanism 66,such as increasing a speed thereof, or reversing a direction of rotationthereof, or generally slowing the operation of one or more systems ofthe combine. Here, it should be noted that FIGS. 2 and 5 illustratedischarge 112 configured in a chopping mode, for delivering crop residueto chopper 68, and that a set or sets of pressure values can be storedand referred to by control 84 for determining onset or existence of aplugging condition in that configuration. Other sets of pressurecondition information can be stored when discharge 112 is configureddifferently, for instance, for discharging crop residue through lowerrear opening 70 without chopping, or by opening hood ceiling 76 forconveying crop residue from the rear of combine 20 in a windrow.

Referring also to FIGS. 6 and 7, schematic illustrations of the rear endof combine 20 when unobstructed (FIG. 6) and when plug, such as by aplug 102 (FIG. 7) are illustrated. Here, it is evident that the extentof an area for escape of air through discharge 112 is smaller as aresult of the presence of plug 102, so as to result in the increasedpressure condition A1 (FIG. 7) which is detected by sensor 100 of thepresent invention.

Although an exemplary embodiment of the system and method for detectingonset or actual plugging conditions in a discharge of a combine has beenshown and described with reference to particular embodiments andapplications thereof, it will be apparent to those having ordinary skillin the art that a number of changes, modifications, or alterations tothe invention as described herein may be made, none of which depart fromthe spirit or scope of the present invention. All such changes,modifications, and alterations should therefore be seen as being withinthe scope of the present invention.

1. An agricultural combine comprising: a body defining a space, thespace having forward and rearward portions, the forward portioncontaining a separating system, and a rear opening spaced rearwardly ofthe separating system; an crop residue propeller disposed in therearward portion of the space between the separating system and the rearopening and operable for propelling a flow of crop residue rearwardlyalong a crop flow path from the separating system toward a rear end ofthe space; a cleaning system disposed in the forward portion of thespace below the crop residue propeller and including a fan disposed fordirecting a flow of air rearwardly through an air flow channel throughthe space between the cleaning system and the propeller, the cleaningsystem further including a beater pan disposed beneath the propeller andabove the air flow channel and a sieve disposed below the airflowchannel; and an air pressure sensor disposed in the forward portion ofthe space, the air pressure sensor disposed below the beater pan andabove the sieve, the air pressure sensor operable for sensing an airpressure condition in the forward portion which is indicative of aplugging condition toward the rear end of the space, wherein the forwardportion is substantially free of plugging thereby increasing thereliability of monitoring the onset of plugging in the rearward portion.2. The agricultural combine of claim 1, wherein the air pressure sensoris mounted in a side wall of the body adjacent to the air flow channel.3. The agricultural combine of claim 1, further comprising a cropresidue chopper disposed in connection with the rear opening, and aconveyor mechanism in a rear region of the space in a position forreceiving at least a portion of the flow of the crop residue from thepropeller and conveying the received flow into the chopper, the airpressure sensor being operable for sensing an air pressure conditionindicative of plugging of the conveyor mechanism.
 4. The agriculturalcombine of claim 3 further comprising a control in connection with theair pressure sensor, and a device for determining a speed of theconveyor mechanism, the control being operable for determining existenceof a plugging condition as a function at least in part of a sensed airpressure and a determined speed of the conveyor.
 5. The agriculturalcombine of claim 1 further comprising a control in connection with theair pressure sensor, and a device for determining a speed of the fan,the control being operable for determining existence of a pluggingcondition as a function at least in part of a sensed air pressure and adetermined speed of the fan.
 6. The agricultural combine of claim 1,wherein the air pressure sensor is disposed adjacent to or in the airflow channel and is operable for sensing an air pressure conditiontherein indicative of a reduced crop residue flow condition in the rearend of the space.
 7. An agricultural combine comprising: a body defininga space the space having forward and rearward portions, the forwardportion containing a separating system, and a rear opening spacedrearwardly of the separating system; a rotary beater disposed in therearward portion of the space between the separating system and the rearopening and operable for propelling a flow of crop residue rearwardlyalong a crop flow path from the separating system toward a rear end ofthe space; a cleaning system disposed in the forward portion of thespace below the rotary beater and including a fan disposed for directinga flow of air rearwardly through an air flow channel through the spacebetween the cleaning system and the beater, the cleaning system furtherincluding a beater pan disposed beneath the rotary beater and above theair flow channel and a sieve disposed below the airflow channel; and anair pressure sensor disposed in the forward portion of the spaceadjacent to or in the air flow channel and operable for sensing an airpressure condition in the forward portion which is indicative of aplugging condition in the rear end of the space, wherein the forwardportion is substantially free of plugging thereby increasing thereliability of monitoring the onset of plugging in the rearward portion.8. The agricultural combine of claim 7, wherein the air pressure sensoris mounted in a side wall of the body adjacent to the air flow channel.9. The agricultural combine of claim 7, further comprising a cropresidue chopper disposed in connection with the rear opening, and aconveyor mechanism in a rear region of the space in a position forreceiving at least a portion of the flow of the crop residue from thebeater and conveying the received flow into the chopper, the airpressure sensor being operable for sensing an air pressure conditionindicative of plugging of the conveyor mechanism.
 10. The agriculturalcombine of claim 9 further comprising a control in connection with theair pressure sensor, and a device for determining a speed of theconveyor mechanism, the control being operable for determining existenceof a plugging condition as a function at least in part of a sensed airpressure and determined speed of the conveyor.
 11. The agriculturalcombine of claim 7, further comprising a control in connection with theair pressure sensor, a device for determining a speed of rotation of thefan, and the control being operable for adjusting a speed as a functionat least in part of a sensed air pressure and a determined speed. 12.The agricultural combine of claim 1, further comprising a control inconnection with the air pressure sensor, the control is programmable tostore air pressure values sensed by the air pressure sensor, the controlis programmable to differentiate between ranges of air pressure valuesfor determining the onset of a plugging condition, wherein when aplugging condition as a function of the sensed air pressure has beendetermined to exist by the control, the control is configured toautomatically adjust at least one operating parameter in order to clearthe plugging condition.